Thread pull-off for sewing machines



A ril 2, 1963 w. E. PATRICK 3,083,661

THREAD PULL-OFF FOR SEWING MACHINES Filed Oct. 15, 1959 4 Sheets-Sheet 1IN VEN TOR. William E. Patrick WITNESS Fig A ril 2, 1963 w. E. PATRICK3,083,661

THREAD PULL-OFF FOR SEWING MACHINES Filed Oct. 13, 1959 4 Sheets-Sheet 2F i 3 INVENTOR.

9 William E. Patrick WITNESS m mym April 2, 1963 w. E. PATRICK THREADPULL-OFF FOR SEWING MACHINES 4 Sheets-Sheet 3 Filed Oct. 15, 1959 Fig.4

A ril 2, 1963 w. E. PATRICK ,0

THREAD PULL-OFF FOR SEWING MACHINES v Filed Oct. 15, 1959 4 Sheets-Sheet4 INVENTOR.

Fig 5 William E. Pafrick WITNESS BY 9% W44 yaw TORNEY 3,083,661 PatentedApr. 2, 1963 3,683,661 THREAD PULL-OFF FQR SEWING MAQHINES William E.Patrick, Colonia, Ni, assignor to The Singer Manufacturing Company,Elizabeth, N..l., a corporation of New Jersey Filed Oct. 13, 1959, Ser.No. 846,130 3 Claims. (1. 112-242) The present invention relates tosewing machines and, more particularly, to a thread pull-off for sewingmachines.

In a sewing machine, the needle thread is usually run from a supplythrough a tension device and take-up mechanism to the needle and then tothe work. At stitch setting, the take-up mechanism tensions the threadby pulling on it between the end that is anchored in the work and thetension device, which is adjustable and which at a particular settingoffers a certain specific resistance to drawing thread from the supply.The tension device determines the amount of tension that the take-upmechanism can apply to the thread in that any tension applied to thethread greater than the resistance oifered by the tension device at theparticular setting will pull thread through the tension device from thesupply. By limiting the tension that can be applied to the thread, thetension device determines the stitch setting characteristics of themachine. The total tension on the thread, however, is not solely afunction of the tension device since the thread guides and otherelements of the thread handling system also offer a resistance to thepassage of the thread and, in addition, there is a certain pull requiredto draw the thread from the supply. The resistance to the passage of thethread otiered by most of the various elements in the thread system issubstantially constant 'from stitch to stitch. This is not always true,however, of the etfort required to pull thread off the supply. Forexample, in a family type sewing machine, the thread supply usuallyconsists of a thread spool mounted on a spool pin on the top of thebracket arm of the machine and when thread is pulled from the supply,the entire spool is rotated. Pulling thread from the supply occurs in avery small portion of the sewing cycle and is very quick so that, ineflfect, the thread is pulled in jerks.

Assuming that on one particular stitch the thread is taut between thetension device and the spool, all the thread pulled into the threadsystem at the end of that stitch must be pulled ofi the spool. As thespool is jerked to supply the thread, because of inertia of the spool,it will tend to continue rotating after pulling has ceased and will thusspill a certain amount of thread. Consequently, on the subsequentstitch, there is slack thread between the tension device and the threadspool so that no thread need be drawn off the spool. When the slackthread is consumed, thread must again be drawn off the spool. The effortrequired to jerk the thread off the spool has a considerable effect uponthe total tension placed on the thread so that there is a substantialvaria tion between the total tension on the thread on one stitch whenthread must be drawn from the spool and the subsequent stitch when thereis slack thread available. The result, of course, is erratic stitchsetting.

In zigzag sewing machines, for example in sewing a satin stitch, aconsiderable amount of thread is required for each stitch and, inaddition, a very low tension setting is required. In such a situation,the problem is aggravated since spilling of thread from the spool ismore pronounced and the efiects of the variations in the total tensionare greater and are more readily apparent because the bobbin thread islaid in a very erratic and very noticeable pattern.

vide a thread pull-01f means for a sewing machine, which means willprovide a slack thread on the supply side of the tension device forevery stitch, thereby efiectively isolating the thread supply from thethread tension system and providing a more nearly uniform threadtension. More particularly, it is an object of this invention to providea thread pull-ofi means that is simple and economical, and at the sametime, effective and reliable. The above objects have been attained inaccordance with this invention by the provision of a thread pull-oftfinger mounted on the needle bar driving crank and operable between apair of spaced thread guides to pull a predetermined quantity of threadfrom the supply, the device being disposed between the thread supply andthe tension device of the sewing machine and thereby providing slackthread on the supply side of the tension so that the stitch will be setagainst the tension alone and will not be affected by the varying forcerequired to pull the thread from the supply. The arrangement of thepulloff finger on the needle bar driving crank provides for the use of asimple and economical element having an orbital movement which, in usefor example with a link take up, is automatically optimumly timed withrespect to stitch setting, will uniformly engage and release the threadupon each stitch, can be substantially concealed within the frame of themachine, and comprises a smooth and readily balanced action.

Having in mind the above and other objects that will be evident from anunderstanding of this disclosure, the invention comprises the devices,combinations and arrangements of parts as illustrated in the presentlypreferred embodiment of the invention which is hereinafter set forth insuch detail as to enable those skilled in the art readily to understandthe function, operation, construction and advantages of it when read inconjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary elevational view of the head end of a sewingmachine embodying the present invention,

FIG. 2 is a fragmentary detail view in elevation of that portion of FIG.1 showing the thread pull-off, but with the parts in a diflerentoperative position,

FIG. 3 is a fragmentary vertical sectional view longitudinally of thesewing machine of FIG. 1,

FIG. 4 is a fragmentary vertical sectional view taken substantially onthe line 44 of FIG. 3,

FIG. 5 is a schematic view showing the paths of motion of the take-uplever and the pull-01f finger of the machine.

With reference to the drawings, there is illustrated a fragmentaryportion of a zigzag sewing machine embodying the present invention, andparticularly the sewing machine forming the subject matter of the UnitedStates patent of Johnson, No. 2,862,468. The machine includes a framehaving a bed defining a work supporting surface 1 and a bracket arm 2overhanging the work supporting surface 1 and terminating in a head 3.

Mounted in the head 3 for vertical endwise reciprocation is a needle bar4 carrying a needle 5 at its lower end. The needle 5 is adapted topenetrate work on the work supporting surface 1 and cooperatetherebeneath with a loop taker (not shown) in the formation of lockstitches. For zigzag stitching, the needle bar 4 is adapted to beoscillated to vibrate the needle 5 laterally of the line of feed. Forthis purpose, the needle bar 4 is supported in the lower portion of thehead 3 by a spherical bearing 6 which provides for endwise reciprocationof the needle bar 4 and for universal pivotal movement as defined by thebearing 6. At its upper end, the needle bar 4 is journaled in a bore 7in a gate member 8 that is pivotally mounted on a presser bar bushing 9and is Accordingly, it is an object of this invention to pro-connectedby a link 10 to a zigzag mechanism for im- 3. parting vibrations to theneedle bar 4 for moving the needle 5 laterally of the line of feed. The.details of the above mechanism form no part of the present invention,and so are not herein disclosed. However, the disclosed mechanism issubstantially the same as in the above mention Johnson patent, No.2,862,468, to which reference may be had for a. more detailed disclosurethereof. a Endwise reciprocation is imparted to the needle bar 4 by acounterbalanced crank 11 mounted on the head end of a main shaft 12journaled longitudinally of the bracket arm 2 A crank pin 13 is securedin the crank 11 by a set screw 14. One end of a connecting link 15 isprovided with a hub 16 having a bore for receiving the crank pin 13, thehub 16 having a reduced portion 17 received Within a recess in the crank11. The other end of the link 15 has a bore 19 slidably receiving a pin20 having integral thereofspaced cheeks 21 disposed upon opposite sidesof the needle bar 4. The cheeks 21 support a cross pin 22 having avertical bore 23 for receiving the needle bar 4 and a set screw 24 forlocking the same relatively to the needle bar. r V V The take-upmechanism of the machine is of a conventional link type and comprises atake-up lever 25 pivotally mounted atone end on the crank pin 13 andhaving a free opposite end extending through a vertical slot 26 to theexterior of the head. A threading eye 27 is formed in the free end ofthe take-up lever. Intermediate its ends, the take-up lever25 ispivotally connected by a pin 28 to one end of an anchor link 29 that ispivotally connected at its other end by a pivot screw 38 to a boss 31formed in the head 3.

The thread pull-off mechanism in accordance with this inventioncomprises a planar thread pull-off element 32 formed of sheet metal andsecured to the needle bar driving link-15. The element 32 is providedwith a hole 33 receiving the reduced end 17 of the'hub 16 of the link 15and has an arm 34 secured to the face of the link -15 by a screw 35. Theelement 32 has a pull-01f finger 36 having a free end 37 formed on theunderside thereof with a thread-engaging surface 38. Upon rotation ofthe crank 11, the free end 37 of the finger 36 is projected through avertically-arranged slot 39in the front wall of the head 3.

Secured'on'the front face of the head 3, as by n'vets 40, is a plate 41having'a slot 42 substantially coinciding with the slot 39 in the head3. The plate 41 carries a first thread guide 43 on one side of the slot42 and a second guide 44 on the other side of the slot 42. The guides43and 44 are designed to direct the thread lead laterally across the slot42 at a point intermediate the ends of the slot 42.

The machine includes a thread tension device 45, for example, of thetype illustrated in the United States patent application of Johnson,Serial No. 692,323, filed October 26, 1957, now Patent No. 2,955,775.Briefly, this thread tension device comprises a mounting stud 46 onwhich are arranged a' plurality of tension discs 47 that are biasedintoengagement with each other by a spring (not shown) disposed within apair of telescoping spring covers 48, the compression of the spring'andthus the tension imposed upon a thread adapted to pass between the discs47 being regulated by an adjusting nut 49. The tension device alsoincludes a check spring 50 and a guard plate 51. A stop plate 52 isdisposed between the tension device and the face of the-head 3 and isadjustably secured thereto by a screw 53. The stop plate 52 iucludesanabutment 54- for the check spring '50 and a guar'd55 to facilitatethreading. Behind the stop plate 52 there: is disposed a plate 56carrying thread guides 57 and 58.

r The thread supply in the illustrated machine comprises a thread spool59 mounted on a spool pin 60 on the top of the bracket arm 2. From thespool 59, the thread T passes through a guide 61 to the guide 43 of theplate 41 andthen laterally across the slot 42 to the guide 44.

4 From the guide 44, the thread passes through the tension device 45'between a pair of the tension discs 47 and around the stud 46, through aguide 62 formed on the guard plate 51, the check spring 50, guide 58,the eye 27 of the take-up lever 25, the a-guide 57, guide 63 mountedbeneath the head 3, and a pair of guides 64 and 65 on a needle clamp 66,to the eye of the needle 5.

With reference to FIG. 5, during operation of the machine, the crank 11is rotated to move the crank pin 13 in the direction of the arrow. Asthe needle bar approaches the top of its stroke, the take-up lever 25 issimultaneously approaching the top of its stroke. At this time, thetake-up lever is pulling the sewing thread to set the stitch in the workand, in the final movements, drawing thread into the system through thetension device from the supply to replace the thread that was consumedin the stitch. The take-up lever 25 then begins to descend to make slackthread available for forming the next stitch and the needle bar 4 beginsto descend. It is at this time in the cycle that the thread pull-offacts to pull thread from the supply to make slack thread available onthe supply side of the tension device. In FIG. 5, there is illustratedthe path of movement at a point P onrthe thread engaging surface 38 ofthe free end v37 of the finger 36. The free end 37 of the finger 36 isprojected through the slot 39 at a point above the thread lead] betweenthe guides 43' and 44 and then moves downwardly. The thread is isolatedby the tension device 45 from the thread system of the machine so thatas the thread lead between the guides 43 and 44 is expanded by thefinger 36, as illustrated in FIG. 2, a certain amount of thread ispulled from the spool 53. Thereafter, the free end of the finger 36 isdrawn back into the head 3 and moves upwardly to begin another pull-offstroke, the upward movement of the finger 36 leaving slack threadbetween the guides 43 and 44 which thread is available for when thetake-up mechanism again pulls thread into the system through the tensiondevice 45.

amount of slack thread left between the guides 43 and 44 which is thefixed amount initially provided by the pull-01f mechanism less theamount drawn into the thread system to replace the thread consumed inthe stitch. When the pull-off mechanism is again operated,

. the thread limb between the guides 43 and 44 is expanded to the sameextent as on the previous stitch, drawing from the spool 53 only theamount of thread'required to replace the thread drawn from there intothethread system.

ln'accordance with this invention, there has been provided a novel,simple and effective thread pull-01f mechanism that provides slackthread on. the supply side of the tension andthereby completely isolatesthe thread supply from the system so that it will be unable to effectthe tensioning of the needle thread at stitch setting. At the same time,the thread pull-01f mechanism in accordance with this invention issubstantially concealed in that it the work, and is protected so that itis not subject to damage. 7

Numerous alterations of the structure herein disclosed will suggestthemselves to those skilled in the art. How-' ever, it is to beunderstood that the present disclosure relates to a preferred embodimentof my invention which is for purposes of illustration only and not to beconstrued as a limitation of the invention. All such modifications whichdo not depart from the spirit of the invention are intended to beincluded within the scope of the appended claims.

Having thus described the nature of the invention, what I claim hereinis:

1. In a sewing machine having a frame, a needle bar mounted in saidframe for endwise reciprocation and having a work-penetrating stroke anda return stroke, a rotary shaft journaled in said frame, a crank on saidshaft, a needle bar driving link pivotally connected at one end to saidcrank and at the other end to said needle bar for imparting endwisereciprocation to said needle bar upon rotation of said shaft, a threadtake-up mechanism mounted in said frame, means operatively connectingsaid take-up mechanism and said shafit for actuating said take-upmechanism in synchronism with said needle bar to effect a maximumtake-up action substantially simultaneously with the end of the returnstroke of said needle bar, a tension device disposed between saidtake-up mechanism and the thread supply and a thread pull-oft mechanismdisposed on the thread supply side of said tension device and comprisinga pull-ofi element on said needle =bar driving link and having a threadengaging free end movable in a plane parallel to the plane of movementof said link and having a path of movement defined by the movement ofsaid link, said frame having an opening in the plane of movement of thethread engaging end of said pull-01f element, said pull-off elementbeing extended to project said thread engaging end through said openingduring the work-penetrating stroke of said needle and to retract thesame during the return stroke thereof, and thread guides defining athread lead transversely of the path of movement of said thread engagingend of said pull-off element whereby said thread engaging end of saidpull-oh element engages and expands said thread lead during thework-penetrating stroke of said needle and releases said thread leadduring the return stroke of said needle.

2. In a sewing machine having a frame including a head, a, needle barmounted in said head for endwise reciprocation, a rotary shaft journaledin said frame and extending into said head, a crank on said shaft withinsaid head, a crank pin carried by said crank, a needle bar driving linkpivotally connected at one end to said crank pin and at the other end tosaid needle bar for imparting endwise reciprocation to said needle barupon rotation of said shaft, a take-up mechanism comprising a take-uplever pivotally mounted at one end on said crank pin and having a threadeye at the other end, an anchor link pivotally connected at one end toan intermediate point of said take-up lever and at the other end to saidframe, a tension device disposed between said take-up mechanism and thethread supply, and a thread pull-0E mechanism disposed on the threadsupply side of said tension device and comprising a pull-oft element onsaid needle bar driving link and having a thread engaging free endmovable in a plane parallel to the plane of movement of said needle bardriving link and having a path of movement defined by the movement ofsaid link, said head having an opening in the plane of movement of thethread engaging end of said pull-ofi element, said pull-01f elementbeing extended to project said thread engaging end through said openingduring the work-penetrating stroke of said needle and to retract thesame on the return stroke thereof, and thread guides defining a threadlead transversely of the path of movement of said thread engaging end ofsaid pull-ofi element whereby said thread engaging end of said pull-offelement engages and expands said thread lead during the work-penetratingstroke of said needle and releases said thread lead during the returnstroke of said needle.

3. In a sewing machine having a frame including a head, a needle barmounted in said head for endwise reciprocation, a rotary shaft journaledin said frame and extending into said head, a crank on said shaft withinsaid head, a crank pin carried by said crank, a needle bar driving linkpivotally connected at one end to said crank pin and at the other end tosaid needle bar for imparting endwise reciprocation to said needle barupon rotation of said shaft, a take-up mechanism comprising a take-uplever pivotally mounted at one end on said crank pin and having a threadeye at the other end, an anchor link pivotally connected at one end toan intermediate point of said take-up lever and at the other end to saidframe, a tension device disposed between said take-up mechanism and thethread supply and a thread pull-off mechanism disposed on the threadsupply side of said tension device and com-prising a pull-ofl'f elementformed of sheet metal and having a thread engaging free end, means forpivotally mounting said element on said crank pin at one point andreleasably securing said element to said needle bar driving link atanother point for movement of said element in a plane parallel to theplane of movement of said needle bar driving link and having a path ofmovement defined by the movement of said needle bar driving link, saidhead having an opening in the plane of movement of the thread engagingend of said pull-oil element, said pull-ofi element being extended toproject said thread engaging end through said opening during thework-penetrating stroke of said needle and to retract the same on thereturn stroke thereof, said thread guides defining a thread leadtransversely of the path of movement of said thread engaging end of saidpull-oif element whereby said thread engaging end of said pull-oftelement engages and expands said thread lead during the work-penetratingstroke of said needle and releases said thread lead during the returnstroke of said needle.

References Cited in the file of this patent UNITED STATES PATENTS557,730 Trowbridge Apr. 7, 1896 1,133,608 Berger Mar. 30, 1915 1,166,834Hemleb Jan. 4, 1916 1,549,081 "Hohmann Aug. 11, 1925 2,430,084 SmithNov. 4, 1947 2,704,987 Court et al Mar. 29, 1955

1. IN A SEWING MACHINE HAVING A FRAME, A NEEDLE BAR MOUNTED IN SAIDFRAME FOR ENDWISE RECIPROCATION AND HAVING A WORK-PENETRATING STROKE ANDA RETURN STROKE, A ROTARY SHAFT JOURNALED IN SAID FRAME, A CRANK ON SAIDSHAFT. A NEEDLE BAR DRIVING LINK PIVOTALLY CONNECTED AT ONE END TO SAIDCRANK AND AT THE OTHER END TO SAID NEEDLE BAR FOR IMPARTING ENDWISERECIPROCATION TO SAID NEEDLE BAR UPON ROTATION OF SAID SHAFT, A THREADTAKE-UP MECHANISM MOUNTED IN SAID FRAME, MEANS OPERATIVELY CONNECTINGSAID TAKE-UP MECHANISM AND SAID SHAFT FOR ACTUATING SAID TAKE-UPMECHANISM IN SYNCHRONISM WITH SAID NEEDLE BAR TO EFFECT A MAXIMUMTAKE-UP ACTION SUBSTANTIALLY SIMULTANEOUSLY WITH THE END OF THE RETURNSTROKE OF SAID NEEDLE BAR, A TENSION DEVICE DISPOSED BETWEEN SAIDTAKE-UP MECHANISM AND THE THREAD SUPPLY AND A THREAD PULL-OFF MECHANISMDISPOSED ON THE THREAD SUPPLY SIDE OF SAID TENSION DEVICE AND COMPRISINGA PULL-OFF ELEMENT ON SAID NEEDLE BAR DRIVING LINK AND HAVING A THREADENGAGING FREE END MOVABLE IN A PLANE PARALLEL TO THE PLANE OF MOVEMENTOF SAID LINK AND HAVING A PATH OF MOVEMENT DEFINED BY THE MOVEMENT OFSAID LINK, SAID FRAME HAVING AN OPENING IN THE PLANE OF MOVEMENT OF THETHREAD ENGAGING END OF SAID PULL-OFF ELEMENT, SAID PULL-OFF ELEMENTBEING EXTENDED TO PROJECT SAID THREAD ENGAGING END THROUGH SAID OPENINGDURING THE WORK-PENETRATING STROKE OF SAID NEEDLE AND TO RETRACT THESAME DURING THE RETURN STROKE THEREOF, AND THREAD GUIDES DEFINING ATHREAD LEAD TRANSVERSELY OF THE PATH OF MOVEMENT OF SAID THREAD ENGAGINGEND OF SAID PULL-OFF ELEMENT WHEREBY SAID THREAD ENGAGING END OF SAIDPULL-OFF ELEMENT ENGAGES AND EXPANDS SAID THREAD LEAD DURING THEWORK-PENETRATING STROKE OF SAID NEEDLE AND RELEASES SAID THREAD LEADDURING THE RETURN STROKE OF SAID NEEDLE.